A bay is a body of water connected to an ocean or lake, formed by an indentation of the shoreline. A large bay may be called a gulf, a sea, a sound, or a bight. A cove is a smaller circular or oval coastal inlet with a narrow entrance; some coves may be referred to as bays. A fjord is a particularly steep bay shaped by glacial activity.Bays can exist as the estuary of a river, as the estuary of the Parramatta River in Australia. Bays may be nested in each other; for example, James Bay is an arm of Hudson Bay. Some large bays, such as the Bay of Bengal and the Hudson Bay, have varied marine geology.The land surrounding a bay can often block waves and reduce the strength of winds. Thus bays were significant in the history of human settlement because they could provide a safe place for fishing. Later they were important in the development of sea trade as the safe anchorage they provide encouraged their selection as ports.